He actually resides mostly in LA at a place called Gold Base. As outlined in the film, there is an area just outside of LA with the CC where Tuna really wants to go see. He ends up spending most of his time there and never really makes it too much further up the bridge. This is fine by him, his wife is an OT V and he's pretty set moneywise by this point so he keeps on taking his purification rundowns and relationship & study courses. Of course, by 1998 he has probably overdosed on niacin so many times his brain turned half to mush, but it makes him an even better figurehead when paired up with Earl. They're brothers at one point and they get into all kinds of crazy shenanigans after Earl wins the lottery. It's implied that at some point Tuna's money is completely drained and he can't afford his courses anymore, and he goes even crazier since he thinks he needs these to survive (literally, to live.) so he ultimately ends his life just weeks before the cult is brought to legal justice in every country except the USA. It doesn't take long for the pressure to build into some sort of Branch Davidian-esque standoff in every org building in the south. The final and most publicized of these events being in LA (gold base) and Clearwater, Florida.